Originally known as sidewalk-surfing, skateboarding is believed to have been conceived initially in the late 1940's or early 1950's as a surfer's pastime for when the surf was flat. Today skateboarding is considered an action sport and recreational activity surrounding an estimated market of 11.08 million active skaters and $4.8 billion in annual revenue.
The construction of the modern skateboard involves a platform on which a user stands referred to as a “deck,” and a pair of two-wheeled axle assemblies commonly known as “trucks.”
Trucks are the axle assemblies that allow a rider to steer the skateboard through shifting his or her weight. Trucks have an axle or axle hanger that pivots in relation to a baseplate with each end of the axle having an affixed wheel. The two trucks are affixed to the bottom of the deck, one near the front and the other near the back end of the deck, spanning the deck. The trucks are affixed so the axles are perpendicular to the midline and the path of travel. The assembly of the truck allows the axle to pivot about a pivot-axis to generate coordinated perpendicular and parallel articulation of the axle in relation to the deck. The perpendicular articulation of the truck causes deck tilt across the midline, which is beneficial to a rider remaining on the deck while navigating a turn. The parallel articulation causes axle rotation, which further causes the axle to no longer remain perpendicular to the midline. The offset angle of the axle from perpendicular causes the skateboard to take a different path of travel. It will be appreciated that higher levels of perpendicular articulation results in higher angles of tilt, while higher levels of parallel articulation result in higher offset angles translating to tighter turning capability.
The general construction of a truck assembly includes a baseplate that has provisions for the constraint of an axle at two points. These two points of constraint, coincident with the pivot-axis are a pivot point and a threaded rod referred to as a king-pin. One portion of the axle hanger is inserted into the pivot recess and another portion of the axle hanger has an aperture, which is placed over the king-pin with a semi-elastic bushing placed on either side of the aperture. A nut is then threaded over the open end of the king-pin to compress the semi-elastic bushings. The compression level and elasticity of the bushings control the ease of articulation.
The baseplate angle is the main influencing factor in how much parallel articulation trucks have in relation to perpendicular articulation. It is known to those skilled in the art that the baseplate angle is the angle about which the pivot-axis that the axle articulates. A baseplate angle of 0-degrees would result in a truck having only perpendicular articulation. A 90-degree baseplate angle would result in a truck having only parallel articulation. A 45-degree angle would result in a truck having a 1:1 perpendicular to parallel articulation ratio.
Skateboards vary in size and purpose. Some skateboards may have a more rigid deck with trucks that provide less articulation suitable for trick riding. Other skateboards, such as “longboard” skateboards, are intended to act more like a surfboard. Longboard skateboards typically have longer and more flexible decks and trucks that allow for more articulation. Longboards also typically have a larger baseplate angle as the longer deck needs maneuverability. Many longboards use trucks with a baseplate angle in excess of 45-degrees to allow for increased maneuverability. A standard baseplate angle for a longboard truck is typically between 50-degrees and 52-degrees.